In people with type 1 diabetes, the immune system kills off insulin-producing beta cells of the pancreas needed to control the amount of glucose in their bloodstream. As a result, they must monitor their blood glucose often and take replacement doses of insulin to keep it under control. Transplantation of donated pancreatic islets—tissue that contains beta cells—holds some promise as a therapy or even a cure for type 1 diabetes. However, such donor islets are in notoriously short supply [1]. Recent advances in stem cell research have raised hopes of one day generating an essentially unlimited supply of replacement beta cells perfectly matched to the patient to avoid transplant rejection.

A couple of years ago, researchers took a major step toward this goal by coaxing induced pluripotent stem cells (iPSCs), which are made from mature human cells, to differentiate into cells that closely resembled beta cells. But a few things were troublesome. The process was long and difficult, and the iPSC-derived cells were not quite as good at sensing glucose and secreting insulin as cells in a healthy person. They also looked and, in some ways, acted like beta cells, but were unable to mature fully in the lab. Now, an NIH-funded team has succeeded in finding an additional switch that enables iPSC-derived beta cells to mature and produce insulin in a dish—a significant step toward moving this work closer to the clinical applications that many diabetics have wanted.

In healthy people, beta cells mature and develop their full capabilities soon after birth, usually as infants begin to take in nutrients. In the new study, reported recently in the journal Cell Metabolism, Michael Downes and Ronald Evans of the Salk Institute for Biological Studies, La Jolla, CA, and their colleagues wanted to know how gene expression changes in beta cells as they become fully functional [2]. To find out, they compared gene expression in cells isolated at different points in development. Their search led them to a protein receptor inside cells known as ERR-gamma. They discovered that ERR-gamma, which binds DNA to influence the expression of other genes, is present at much higher levels in adult compared to fetal beta cells.

As luck would have it, Downes and Evans had studied the ERR-gamma receptor before in a very different context. ERR-gamma is found at naturally high levels in the muscles of endurance runners [3]. In fact, mice with muscles expressing high levels of ERR-gamma can run much farther than an average mouse. The receptor appears to function as a metabolic switch, endowing cells with the extra energy needed to keep on going, in this case, to the finish line.

Downes and Evans now show that ERR-gamma also gives beta cells the energy and endurance needed to respond continuously to glucose by producing insulin. As evidence for the importance of ERR-gamma, the researchers found that mice whose beta cells lacked this protein receptor were unable to respond properly to a spike in glucose. When they forced stem-cell-derived beta cells to produce ERR-gamma, the cells began responding to glucose like fully mature cells, without first having to mature in a living animal.

The researchers compare what happens in beta cells lacking ERR-gamma to a power outage. All of the wires, switches, and other elements may be ready to go. But the cell doesn’t have the energy required to activate them. With ERR-gamma in place, the power switches on, and the cell can begin its work to produce insulin.

To further test the lab-grown beta cells, the researchers inserted them into mice with type 1 diabetes. Those fully mature, transplanted cells soon began producing insulin to rescue the animals from their diabetes.

The new discovery now makes it more feasible to create fully functional beta cells, without relying on other mysterious maturation processes to occur after transplantation. Before clinical trials in humans can begin, however, the lab-grown beta cells must first be tested in animals. In the meantime, there are still plenty of questions yet to be resolved, including how, when, and where beta cells should be delivered. It will also be important to learn how long the replacement beta cells will function after transplantation.

The good news is that this new work shows continued progress toward one of stem cell therapy’s many promising applications: to improve the lives of the many thousands of Americans living with type 1 diabetes.

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This method will make it easier, perhaps, to generate islet cells for transplantation. However, this report lacks context. It is important to point out that there are two other major efforts to develop islet cells to treat diabetes. One is already in Phase I clinical trials; Viacyte, funded by the California Institute for Regenerative Medicine, uses encapsulated human embryonic stem cell-derived islet cells. The other is in Doug Melton’s lab at Harvard, using a more complicated method to make mature islet cells. Since Type I diabetes is an autoimmune disease, an autologous iPSC approach is pointless. The real breakthroughs will be methods to protect the transplanted cells from the host’s immune system.

This is a great news; however, the production of iPSC are going to be from the same patient. So, it going to be destroyed by immune system because type I diabetes is an autoimmune disease. The probable solution is that find way to cover beta cells from immune system after transplant of iPSC.

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About the NIH Director

Francis S. Collins, M.D., Ph.D.

Appointed the 16th Director of NIH by President Barack Obama and confirmed by the Senate. He was sworn in on August 17, 2009. On June 6, 2017. President Donald Trump announced his selection of Dr. Collins to continue to serve as the NIH Director.